Aquatic Plant Management > Chemical Treatment 2005 - 2007
Flowering Rush Spraying, August 18 - 27, 2008
Professional lake Management Company, from Pequot Lakes, Minnesota, applied the herbicide Habitat to Flowering Rush found in portions of Lakes Detroit, Curfman, Muskrat, Sallie, Melissa, and Mill, and segments of the Pelican River, between August 18 and August 27, 2008. The company used a variety of equipment, including back-pack sprayers in some areas.
Using a fixed nozzle spray system mounted on an airboat, operator Patrick Selter applies Habitat to a dispersed stand of Flowering Rush in water 4 feet deep on the North Shore of Big Detroit. For more photos, click here.
~ NEW ~
PRWD Flowering Rush Management
Click on the following links to open up documents
2008 FR Treatment Report
Crush the Rush ~ Ways You Can Help
FR Control Efforts (historical/current) and
Future Control Strategies
Pelican River Watershed District
2007 Flowering Rush Herbicide Treatments
(Click on title for a printable version with pictures)
2007 treatments of flowering rush infestations took place in lakes Detroit, Melissa, Sallie and Deadshot Bay July 11Ė19. This yearís treatment program followed what was generally regarded as a successful treatment program in 2006. In most cases the infested areas responded to treatment by shrinkage of the infestation or by reduced density of plants.
At seven test sites stems counts indicated reduction in plant densities by 50 percent or more. Pictorial comparisons also support claims of 2006 success (See examples elsewhere on the Districtís web-site).
Note that it is not possible to completely eradicate Flowering Rush. The herbicide does not impact submerged plants, including young ones. Such plants can be expected to appear above the water surface in a subsequent year. Hence, it is anticipated that several years will be required to achieve a high degree of control.
After the 2006 treatment some areas did not appear to be helped. It is believed that these areas either inadvertently escaped treatment, or were disturbed shortly after treatment, possibly by boats or waves.
The 2007 treatment program occurred about two weeks earlier than in 2006; this yearís earlier application was somewhat exaggerated from the plantís perspective because of the plantís somewhat delayed development in comparison to the previous year.
The 2006 and 2007 treatments were authorized by the DNR after three years of testing on several sites on Big and Little Detroit, Deadshot Bay (Curfman), Melissa and Sallie. In 2006 and 2007 the chemical herbicide imazapyr (which is made available under the trademark Habitat) was applied to all homogeneous stands of emergent flowering rush.
Treatment locations in 2007 were very similar to those in 2006 (See 2006 Executive Summary for map). Nearly all of the treated sites on Sallie and Melissa are very small, often only a few isolated spears, but including clumps up to four feet in diameter. On Big, Little Detroit and Curfman the treatment areas are quite a bit larger, ranging in size from 6-foot clumps, to more than an acre.
Treatments were carried out by Mr. Denton Offutt, a licensed herbicide applicator, from a specially adapted pontoon boat. The Habitat (Imazapyr) was mixed with a surfactant to promote adhesion of the herbicide to the plant material. A sprayer boom was used for larger treatment areas; a high pressure sprayer was used on smaller stands and those in shallow water.
Just under 33 gallons of Habitat concentrate were applied to about 87 acres on the five lake basins (74 acres on Big, Little Detroit, and Curfman). This yearís total cost was $58,000 down somewhat from last year because of carry-over stocks of chemical.
The success of this yearís treatment program will be evaluated in June, 2008.
prepared by Dick Hecock, August 2007
2007 Flowering Rush Comparisons
(click on title to download report)
Pelican River Watershed District
2006 Flowering Rush Herbicide Treatments
(click on title for a printable version)
Extensive treatments of flowering rush infestations were undertaken from late June through early August. This yearís treatment program grew out of three years of tests on Big and Little Detroit, Deadshot Bay (Curfman), Melissa and Sallie. The chemical herbicide imazapyr (which is made available by BASF under the trademark Habitat) was applied to all homogeneous stands of emergent flowering rush. These applications were authorized by the DNR.
Most of the 2006 treated sites were very small, rarely more than a few isolated spears, up to clumps that were four feet in diameter. These smaller sites were mostly found on Melissa and Sallie. The larger treatment sites were mainly found on Big, Little Detroit and Curfman.
Just under 37 gallons of Habitat concentrate were applied (together with a surfactant to promote adhesion of the herbicide to the plant), to about 99 acres on the five lake basins (93 acres on Big, Little Detroit, and Curfman). The total cost was $72,500 of which 75% was for labor.
Handwicking tests were continued on two near-shore sites on Big Detroit Lake, in order to help ascertain the feasibility of small-scale applications.
prepared by Dick Hecock, September 2006
Pelican River Watershed District
2005 Flowering Rush Herbicide Tests
Chemical applications to several flowering rush test plots were performed during the last week of July and into the first week of August, 2005. This yearís testing program built on two previous years of testing at test sites on Big Detroit and Deadshot Bay (Curfman). This yearís effort was primarily focused on the chemical herbicide imazapyr (also known as Habitat) which had shown special promise after last yearís tests.
Habitat (Imazypyr) test site #9, on Big Detroit Lake in June, 2005; nearly total plant removal was obtained from the previous summerís application.
The DNR authorized 2005 testing on Big, Little Detroit and Curfman sites, as well as some on Melissa and Sallie (see map). Stem counts and photographs were taken at specified sample sites. Locations were obtained using GPS.
Most of the 2005 treated sites were very small. The larger sites were mainly found on Big, Little Detroit and Curfman. Habitat was used on all but three sites, where ShoreClear (a Glysophate formulation for lakes) was used. Two of the ShoreClear sites involved handwicking (application of herbicide directly to plants with sponges). Handwicking also was tried on two Habitat sites, but the rest of the Habitat applications were sprayed. Cost of the 2005 herbicide treatments was approximately $13,000.
One month after the treatment, it is possible to see some plant-burn on the ShoreClear sites. However, the Habitat sites have shown little impact from this yearís treatment.That is the same pattern we observed last year at this time, so we are hopeful that next spring will show good results.
prepared by Dick Hecock, August, 2005